1. Field of the Invention
The present invention relates to rubber waste disposal, particularly to a rubber waste disposal apparatus and method of treating rubber waste such as old tires (including used tires), defective products of manufacturing, rubber waste, and the like.
2. Description of the Background Art
In these few years, the disposal of refuse vulcanized rubber such as old tires (including used tires) has become a major social issue due to the insufficiency of disposal facilities. From the economic standpoint of exhaustion of the resource, it is strongly desired to treat this refuse vulcanized rubber and recover the same as a resource for effective recycling, in converting and collecting refuse vulcanized rubber as a practical substance, the refuse vulcanized rubber is preferably in a comminuted state. The conventional comminuter for refuse vulcanized rubber was mainly based on mechanical method such as shearing, crushing, or impacting on the vulcanized rubber. The vulcanized rubber was pulverized into small particles such as approximately 20-30 meshes, for example. This pulverization process required large motive energy and time since pulverization of the vulcanized rubber by mechanical force was inefficient due to its elastic property. There was a disadvantage that conversion of refuse vulcanized rubber into utility material was extremely costly and not cost-justified.
A method of treating old tires is proposed to comminute vulcanized rubber by applying a mechanical external force on the rubber in a vulcanized state in an atmosphere of a mixture of gases including ozone and air (Japanese Patent Publication Nos. 53-35666, 54-4487, etc.). According to this method of treating old tires, the old tire is removed of the bead portion by a cutter and cut into 16 pieces radially to result in cut pieces. The cut pieces are placed into a sealed container. This sealed container is provided with two plates facing each other so as to repeatedly apply shearing crushing force and agitation. The sealed container has a duct to introduce ozone-containing air therein and a duct to output the exhaust of the air containing ozone from the other side. The cut up pieces are subjected to the chemical process of double bonding in the rubber molecules being broken due to oxidation of rubber caused by ozone and the mechanical stress by an external force simultaneously to be readily comminuted.
Prior to the decomposition of the old tire, the tire must be cut into a plurality of pieces by physical means such as a cutter. This method is complicated with regards to the decomposition means for old tires (including used tires). Also, it is difficult to avoid increasing the running costs associated with the implementation and use of mechanical means for cutting pieces.
In order to facilitate the treatment of rubber waste such as old tires (including used tires) and carry out the treatment of waste disposal at low cost, there is provided a rubber waste disposal apparatus including a sealed tank, an ozone generator to generate ozone in the tank, and a device to apply vibration on the rubber waste placed in the tank (Japanese Utility Model Laying-Open No. 5-18654, and the like). This rubber waste disposal apparatus is provided with a vibration device that applies vibration mechanically or by supersonic waves on the rubber waste in the Lank. The rubber waste in the tank is comminuted into powder by filling the tank with ozone and then applying vibration on the rubber waste by means of the vibration device.
However, there were cases where decomposition of the rubber waste was not promoted sufficiently since a vibration device to apply vibration is employed as the mechanical action means on the rubber waste in such a rubber waste disposal apparatus. The treatment of the rubber waste was extremely time-consuming. It was difficult to treat a great amount of rubber waste in a short period of time.
A rubber waste disposal apparatus including a work chamber, a device to supply ozone-containing gas to the work chamber, and a mechanical deformation device for the product that is to be reprocessed is disclosed in WO99/14026 and the like for the purpose of recycling efficiently refuse rubber waste. The deformation device of the rubber waste disposal apparatus is formed of at least two members, one of which is attached so as to be movable with respect to the other member. The rubber waste disposal apparatus is attached with a protruding tool provided so as to engage with the product to be recycled. Specifically, this rubber waste disposal apparatus shown in FIG. 5 includes a chamber 52 where a used tire 51 is to be reprocessed. Two deformation device members 53 and 54 connected to motive energy drivers 55 and 56 are provided in chamber 52. Protruding tools 57 and 58 are attached to deformation device members 53 and 54. Although not shown, a system supplying ozone-containing gas into the chamber is also provided. Used tire 51 is set between the two deformation device members 53 and 54. One of the deformation device members in chamber 52 is driven by the motive energy driver towards the second deformation device member, whereby used tire 51 is subjected to compression deformation. Then, one of deformation device members 53 and 54 exhibits a twisting motion, whereby used tire 51 is subjected to compression and twisting strain.
When the size of the used tire to be processed is altered, this rubber waste disposal apparatus must have the deformation device members exchanged according to the size of the used tire every time the size changes. There are now various sizes of tires corresponding to the variety of needs of the consumer. It is expected that there will be more used tires of different sizes. Exchanging the deformation device members corresponding to the size of the used tire to be processed every time will degrade the efficiency of processing used tires, leading to an increase in the running cost of the process. Furthermore, effective processing of the used tires will be impeded by the requirement of preparing a plurality of deformation device members corresponding to various sizes.
In view of the foregoing, an object of the present invention is to provide a rubber waste disposal apparatus and method of treating rubber waste to process rubber waste such as old tires (including used tires) efficiently. Here, rubber waste is intended to include used products of various rubber goods, waste from plants, defective products from the fabrication plants, brand new rubber products no longer required, and the like.
According to an aspect of the present invention, a rubber waste disposal apparatus includes a casing, a rubber waste deformation unit provided in the casing to subject the rubber waste to deformation, and an ozone-containing gas supply unit supplying ozone-containing gas into the casing. The rubber waste deformation unit includes at least a pair of cylindrical rollers having a plurality of protrusions projecting outwards, capable of sandwiching rubber waste at the gap therebetween, and a distance setting unit that can set the distance of the gap between the cylindrical rollers.
The gap distance between the cylindrical rollers in the rubber waste disposal apparatus is preferably 5-60% the width of the rubber waste. The ozone-containing gas is preferably a mixture of ozone, air and moisture.
The rubber waste deformation unit preferably includes a rotational speed control unit controlling the rotational speed of the pair of cylindrical roller. The rotational speed of the pair of cylindrical rollers is desirably at least 0.1 rpm.
The rubber waste deformation unit preferably includes a rotation direction control unit controlling the direction of rotation of the pair of cylindrical rollers. The rotation of the pair of cylindrical rollers can be set to one direction during decomposition of the rubber waste.
In the present invention, the ozone concentration of the ozone-containing gas is desirably at least 10 wt %.
In the rubber waste disposal apparatus of the present invention, the ozone-containing gas supply unit preferably supplies ozone-containing gas of high concentration uniformly all over the region of the rubber waste under load of stress between the cylindrical rollers from above and below or from left and right through a plurality of pipes having a plurality of holes, provided vertically or horizontally in close proximity to the pair of cylindrical rollers, whereby reaction with the rubber waste is readily and promptly carried out efficiently under the atmosphere of gas containing ozone of high concentration.
According to another aspect of the present invention, a method of treating rubber waste includes the step of supplying, in an ozone gas atmosphere, rubber waste in a casing including a rubber waste deformation unit with a pair of cylindrical rollers having a plurality of protrusions projecting outwards, capable of sandwiching the rubber waste at the gap therebetween, and adjusting the distance of the gap between the cylindrical rollers to decompose the rubber waste effectively.